IME with dealerships there is always room for negotiating.... stop looking at retail - and look at trade in value for the van. That will give you a rough idea of what kinds of money they have tied up in it. And then you can probably negotiate somewhere inbetween those two numbers. The fact that they JUST got it works against you.... they deal more on cars that have been sitting.... BUT that doesn't mean they won't budge at all.

We are serious used car shoppers - no car is worth "paying" for. I got a 4yr old Sienna under 10K and DH just got a Tundra for 12K (LOW miles).... we just don't mess around with their "games".... DH actually really enjoys car shopping

Most banks and dealerships around here use nada. If I can't get the dealership VERY close to the clean trade in value, I walk away. Besides your paying cash, so they won't have to do any loan paperwork or worry about a trade in either. Don't be afraid to leave and think about whatever offers have been made either.

I'd try to get a few grand off. As PP said, it'll be harder now because everyone is eager to spend their tax refund.
I low ball them and if they don't counter with something reasonable, I walk away. Literally. I never tell them I need a vehicle, even if I do. I point out any and every issue I (or my mechanic DH) find. I don't tell them I'm paying cash until paperwork has began/price has been decided. If they ask, I skirt around the issue. Dealers count on interest money when selling vehicles.